The present invention relates to a thermo-mechanical analyzer.
FIG. 5 is a cross-sectional view of a configuration of a thermo-mechanical analyzer and FIG. 6 is an external view showing a configuration of a sample mounting section.
A test piece 10 is placed on the closed bottom of a cylindrical test piece tube 11, and is subjected to arbitrary loads by a probe 2. A heating furnace 18 is provided about the bottom of the test piece tube 11. The heating furnace 18 is temperature-controlled by a temperature controller (not shown), in order to control the temperature of the test piece 10. The heating furnace 18 can be moved up and down by a moving mechanism (not shown).
The probe 2 is in contact with the test piece 10 at a lower part, is fastened to a probe coupling 12 at an upper part, and is connected to an auxiliary probe 14 using connecting means 13. The auxiliary probe 14 is fixed to a core 15 of a magnetic material and an auxiliary probe 16, respectively. The probe 2 is movable while connected with the probe coupling 12, the auxiliary probe 14, the core 15 and the auxiliary probe 16. The auxiliary probe 16 and so on are supported above the probe 2 by a spring member, balancing mechanism or the like (not shown). The probe 2 is therefore capable of movement in a vertical direction but movement in other directions is restricted.
The test piece tube 11 is fastened to a test piece tube holder 20. The test piece tube holder 20 is then supported by a test piece tube support member 21 using screws. The test piece tube support member 21 is supported at two vertical shafts 24 standing on a base 19 via shaft holders 23. The test piece tube support member 21 can be moved vertically in parallel with the base 19 by a guide screw 25 and a motor 26.
A force generator 17 comprises a coil 17a and a magnet 17b. This force generator can apply an arbitrary load to the test piece 10 via the probe 2 as a result of the mutual action of the coil 17a and magnet 17b fixed to the auxiliary probe 16.
Deformation of the test piece 10 due to heat from the heating furnace 18 or changing load from the force generator 17 is detected by a differential transformer 22 as relative positional changes of the test piece tube 11 and the probe 2. A signal is inputted to a detection circuit (not shown). The differential transformer 22 is fixed to the shafts 24 and a differential transformer support 27, so as to be indirectly fixed to the base 19.
A thermocouple 29 for measuring temperature of the test piece 10 is protected by an insulating tube 30 and extends outwards from the vicinity of the test piece 10 via a hole 20a of the test piece tube holder 20. The thermocouple 29 extending out of the test piece tube 11 is covered by a flexible insulating tube 31 and is connected to a temperature measuring circuit (not shown).
Methods of applying a load to bring about compression, expansion, bending and stretching etc., for this thermo-mechanical analyzer change depending on the shape of the test piece and the objectives of the measurements, and probes are therefore used with this in mind. Operativity when changing probes is therefore one factor influencing the efficiency of measuring operations as a whole.
A test tube and a probe are made of materials which are resistant to heat in a measuring temperature range and have a small expansion coefficient, or existing materials (for example, molten quartz or sintered aluminum etc.). On the other hand, members such as the test piece tube holder 20 and the probe coupling 12 shown in FIG. 5 are made of metal materials etc. Such metal materials are positioned as far as possible above the heating furnace in order to prevent expansion during high temperature measurements. The test piece tube and the upper end of the probe are aligned, and the length of the metal members are made equal in order to offset changes caused by expansion. As a result, the probe connecting means is above the upper end part of the test piece tube. The probe is preferably as long as possible, so that the differential transformer and the force generator may not be influenced by heat from the heating furnaces.
In order to change the probe, there is a method where a probe is taken out from the lower side of the apparatus and a method where the test piece tube is taken out. These methods involve the trouble of dismantling the test piece tube and this makes the operation complex because it is also then necessary to dismantle the thermocouple for measuring the temperature of the test piece that is inside the test piece tube together with the test piece tube. However, if just the test piece tube is removed without extracting the thermocouple in order to avoid complicating the operation, there is a possibility that the relative positions of the end of the thermocouple and the test piece tube will change after reassembly, which is a factor in causing poor reproduction of temperature measurements.
Alternatively, a probe might be removed downward from the apparatus via an opening in the side of the test piece tube. However, the opening is of a size just for changing the test pieces and is made as small as possible in order to guarantee the mechanical strength of the test piece tube. On the other hand, it is necessary to make the length of the probe of a length appropriate for the configuration of the apparatus, as described above, and this length is therefore long compared to the length of the opening for changing test pieces. Therefore, the probe cannot be removed via the opening for changing test pieces. Further, if a hole for probe extraction that is separate to the opening for test piece changing is provided in the bottom of a test piece tube, a space longer than the length of the probe should be maintained at the lower part of a thermo-mechanical analyzer, and this will impose design restrictions. The device therefore has to be made larger than is necessary and this causes problems regarding device installation.
On the other hand, when extracting the probe upward from the apparatus, it is necessary to draw the probe up to a height greater than the height of the apparatus. The height of the thermo-mechanical analyzer and the installation table, together with the length of the probe itself, therefore often become greater than the height of an operator, which has the disadvantage of making this operation difficult to perform.
A small slit sufficient for removing a probe downwards is provided in the side of the lower part of a test piece tube for installing test pieces. The probe is then removed and inserted via this slit-shaped opening. Probes can therefore be changed in confined spaces without removing the test piece tube.